When changing the Android targetSdkVersion from 29 to 30 then the scaling is much smaller:

    // build.gradle:
    defaultConfig {
        resConfig "en"
        minSdkVersion = qtMinSdkVersion
        targetSdkVersion = 30 //qtTargetSdkVersion
    }

Steps to reproduce:

1. Create a new Stacked Qt Quick application in Qt Creator.
2. Select 5.15.2 Android Qt SDK.
3. Change build.gradle as shown above.
4. Uninstall old version of the app if already installed on the Android device.
5. Run. The font size is now much smaller than with targetSdkVersion 29.